JP3757118B2 - Non-contact rotational position sensor and throttle valve assembly having non-contact rotational position sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to, for example, a rotational position sensor that detects a rotational angle of a rotational shaft of a throttle valve (throttle valve) of an internal combustion engine, and more particularly to a non-contact rotational position sensor.
The present invention also relates to a throttle valve assembly provided with such a non-contact rotational position sensor.
[0002]
[Prior art]
As this type of conventional rotational position sensor, those described in Japanese Patent No. 2842482, Japanese Patent No. 2920179, US Pat. No. 5,528,139, US Pat. No. 5,789,117 and US Pat. No. 6,137,288 are known.
[0003]
In these conventional techniques, when the permanent magnet side is a rotor, the magnetic flux density in the circumferential direction in the stator is linearly distributed with respect to the rotation direction of the rotor. In order to prevent the magnetic field distribution in the rotor from being influenced as much as possible by the rotational position of the rotor to which the magnet is attached, the shape of the opposing surface of the rotor and the stator is in a direction perpendicular to the rotational direction. The length is configured to be uniform.
[0004]
[Problems to be solved by the invention]
Thus, since the shape of the opposing surface of a rotor and a stator receives restrictions, when designing suitable for the object apparatus which installs a sensor, there existed a problem that a design freedom was low.
[0005]
The object of the present invention is a non-contact method in which sufficient performance can be obtained even if the length in the direction perpendicular to the rotation direction of the rotor is not uniform in the shape of the opposing surfaces of the magnetic path on the stator side and the rotor side It is to obtain a rotary position sensor.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a part of a stator side magnetic path is formed by, for example, a pair of magnetic plates with an annular or semi-annular permanent magnet forming a rotor interposed therebetween. A magnetic flux converging part as a constricting part for concentrating the magnetic flux is provided in the middle of a closed magnetic path formed therethrough, and a magnetically sensitive element is arranged in the magnetic flux confining part (converging part).
[0007]
In another invention, an annular or semi-annular permanent magnet is attached to the end of the rotary shaft of the throttle valve, and a magnetic material assembly that forms a magnetic passage is attached to a resin cover attached to the main body, The magnetic body assembly is provided with a magnetic flux converging portion, and a magnetic sensitive element is installed in the magnetic flux converging portion.
[0008]
Specifically, the annular or semi-annular permanent magnet is detachably attached to the rotating shaft, and one of the magnetic body assemblies is provided with a hole in the center that is larger than the diameter of the rotating shaft and smaller than the inner diameter of the magnet.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
[0010]
FIG. 1 shows the appearance of the present embodiment, and FIG. 2 is a view showing its internal structure. As shown in FIGS. 1 and 2, in this embodiment, a rotor is formed by a ring-shaped (annular) permanent magnet 10 and a shaft (rotary shaft) 15 that supports the ring-shaped permanent magnet 10. The permanent magnet 10 is sandwiched up and down by magnetic plates (magnetic body assemblies) 11, 12, 13, and 14.
[0011]
The upper magnetic plates 11 and 12 are spaced apart from each other in the horizontal direction. As a result, an air gap (a1, a2, b1, b2) is formed between the magnetic plates 11, 12. The same applies to the lower magnetic plates 13 and 14.
[0012]
On the magnetic plates 11, 12, 13, and 14, projecting magnetic bodies 16, 17, 18, and 19 that form magnetic flux restricting portions (magnetic flux converging portions) are disposed, and holes are formed between the projecting magnetic bodies 16 and 17. An element (magnetic sensitive element) 21 is disposed, and a hall element (magnetic sensitive element) 22 is disposed between the protruding magnetic bodies 18 and 19.
[0013]
The protruding magnetic bodies 16, 17, 18, and 19 that form the magnetic flux restricting portion (magnetic flux converging portion) are formed at target positions with respect to the air gaps a 1, a 2, b 1, and b 2 and at the outer peripheral portion of the magnet 10. The The protruding magnetic bodies 16, 17, 18, and 19 that form the magnetic flux restricting portion (magnetic flux converging portion) are formed integrally with the magnetic plates 11, 12, 13, and 14. It can be attached by gluing or welding.
[0014]
A front view of this embodiment is shown in FIG.
[0015]
The magnetic plates 11, 13 and 12, 14 are arranged facing each other with a uniform gap G1.
[0016]
A uniform small gap g1 is provided between the magnetic plates 11 and 12 and the upper surface of the magnet 10, and a uniform small gap g2 is provided between the magnetic plates 13 and 14 and the lower surface of the magnet 10. Yes.
[0017]
As a result, the gap G1 has a size obtained by adding the small gaps g1 and g2 to the magnet thickness t1.
[0018]
Further, the gap between the projecting magnetic parts 16, 17 and 18, 19 is smaller than the thickness t 1 of the magnet 10.
[0019]
The diameter d of the insertion hole 51 of the shaft 15 provided at the center of the magnetic plates 13 and 14 is set to be equal to or smaller than the inner diameter D of the magnet 10.
[0020]
The diameter d of the insertion hole 51 is at least required to be smaller than the outer diameter D0 of the magnet, but how much it is reduced is determined by the condition of the magnetic path.
[0021]
Further, the central hole 52 and the small gaps a1, a2, b1, and b2 of the magnetic plates 11 and 12 may be omitted. This embodiment will be described later.
[0022]
The diameters d and d0 of the central hole of the magnetic plates (11, 12 and 13, 14) are determined by whether or not the rotary shaft 15 is used as a part of the magnetic path. In the case where the rotating shaft 15 is a non-magnetic material, there is no particular change in performance when the diameters d and d0 of the central holes 51 and 52 of the magnetic plate are made smaller than the inner diameter D of the magnet 10. When 15 is a magnetic body, the magnetic flux at the mounting portion of the magnetic sensitive elements 21 and 22 is affected by the magnetic flux leaking through the rotary shaft 15, so that the magnetic plates (11, 12 and 13, 14 are considered in consideration of this. ), The diameters d and d0 of the central holes 51 and 52 are determined.
[0023]
When the magnetic flux passing through the rotating shaft 15 is positively used, the diameters d and d0 of the central holes 51 and 52 of the magnetic plates (11, 12 and 13, 14) are set small. Conversely, in order to avoid the influence of the magnetic flux passing through the rotating shaft 15, the diameters d and d0 of the central holes 51 and 52 of the magnetic plates (11, 12 and 13, 14) are set large. However, if the hole diameters d and d0 are made larger than the outer diameter D0 of the magnet 10, the air gap between the magnet 10 and the magnetic plates (11, 12 and 13, 14) is increased, and the basic magnetic flux is reduced. The upper limit of the diameters d and d0 of the holes in the center of the plates (11, 12 and 13, 14) is preferably the outer diameter D0 of the magnet 10.
[0024]
The magnetic flux generated by the magnet due to the shape and arrangement of the magnetic members (11 to 14, 16 to 19, and the rotating shaft) and the dimensional relationship of the gaps (g1, g2, G1, G2) is the magnetic sensitive elements 21, 22. Is narrowed down to the two air gaps G2 to which is attached and converges.
[0025]
The leakage magnetic path passing through the rotating shaft 15 is used to adjust the protruding magnetic body portions 16, 17 and 18, 19 so as not to cause extreme magnetic flux saturation.
[0026]
Here, although only one of the Hall elements 21 or the Hall elements 22 functions, two elements are arranged for mutual backup at the time of failure or for check of failure diagnosis.
[0027]
Here, the ring-shaped permanent magnet 10 is generally magnetized in the direction of the rotation axis, as indicated by the arrows in FIG. The direction of magnetization of the ring-shaped permanent magnet 10 is upward in the region of the rotation direction 180 °, and the other regions are downward.
[0028]
The magnetic flux density vector at this time has a distribution as shown in FIG. That is, the magnetic field generated by the ring-shaped permanent magnet 10 is divided into the upper and lower magnetic plates 11, 12, 13, and 14 and passes through the protruding magnetic bodies 16, 17, 18, and 19 and the Hall elements 21 and 22. The direction and strength of the magnetic field passing through the Hall elements 21 and 22 vary depending on the rotational position of the ring-shaped permanent magnet 10.
[0029]
Here, the relationship between the rotational position of the ring-shaped permanent magnet 10 and the amount of magnetic flux passing through the Hall element 21 will be described with reference to FIG. FIG. 5 shows the direction of the magnetic field in the ring-shaped permanent magnet 10.
[0030]
In this rotational position, the region a and the region b are exactly at the same opening angle, the directions of the magnetic fields in the respective regions are opposite to each other, and the magnetic fluxes from the regions a and b cancel each other. Actually, in the vicinity of the boundary between the region a and the region c where the direction of the magnetization distribution is reversed, the magnetization is weakened.
[0031]
For this reason, most of the magnetic flux in the remaining region c passes through the protruding magnetic bodies 16 and 17. This amount is proportional to the area occupied by the region c.
[0032]
Further, the area occupied by the region c is proportional to the rotation angle of the ring-shaped permanent magnet 10. Therefore, the magnetic flux density detected by the Hall element 21 is approximately proportional to the rotation angle of the ring-shaped permanent magnet 10. Thus, by sensing the magnetic flux density detected by the Hall element 21, the rotation angle of the ring-shaped permanent magnet 10, that is, the rotation angle of the shaft 15 can be detected.
[0033]
In this embodiment, the distances a1, a2, b1, and b2 between the magnetic plates 11 and 12 in FIG. 1 are a1 = a2 = b1 = b2, but the present invention is not limited to this. Instead, a1> b1, a2> b2 may be used. Furthermore, it is desirable to set a1 = a2 and b1 = b2. By setting a1> b1, a2> b2, the magnetic coupling between the magnetic bodies 11 and 12 is weakened, and the magnetic flux density detected by the Hall element 21 and the rotation angle of the ring-shaped permanent magnet 10 are reduced. The linear relationship is improved.
[0034]
The upper and lower magnetic plates 11 and 13, and 12 and 14 face each other with a uniform gap G1. The upper and lower magnetic plates 11, 13, 12 and 14 face the permanent magnet 10 while maintaining uniform gaps g 1 (upper gap) and g 2 (lower gap) between them. The gap G1 is larger than the thickness t1 of the permanent magnet 10 by the gap g1 + g2. However, the gaps g3 and g4 between the protruding magnetic bodies 16, 17 and 18, 19 are smaller than the thickness of the permanent magnet 10. With this configuration, the magnetic flux of the permanent magnet 10 can be converged in the protruding magnetic bodies 16, 17 and 18, 19. In this sense, the projecting magnetic bodies 16, 17 and 18, 19 form a magnetic diaphragm portion. That is, the principle of the present invention is to provide the protruding magnetic bodies 16, 17, 18, and 19 as portions where the magnetic flux easily passes between the magnetic plates 11, 13, 12, and 14 and to concentrate the magnetic flux in these portions.
[0035]
In addition, when this sensor is produced at low cost, considering that the mounting accuracy of each part is about ± 0.2 mm, in this embodiment, the ring-shaped permanent magnet 10 and the upper and lower magnetic plates 11, 12, If the width of the air gap between 13 and 14 is 0.5 mm or more, preferably around 1 mm, the influence of the mounting error on the sensor characteristics can be reduced. This is common to the other embodiments described below.
[0036]
The magnetic material has more or less magnetic hysteresis characteristics. Generally, when the magnetic material exceeds 0.5T or 1T, the magnetic hysteresis effect becomes more prominent. In order to increase the rotational position accuracy of the rotational position sensor, it is desirable to use the magnetic hysteresis in a range as small as possible. Therefore, it is desirable that the magnetic flux density inside the magnetic material, typically inside the magnetic plates 11, 12, 13, and 14, is 0.5T or less. This is common to the other embodiments described below.
[0037]
In the present embodiment, the permanent magnet is ring-shaped, but a disk-shaped magnet can have the same function.
[0038]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 shows the external appearance of the present embodiment, and FIG. 7 is a view showing the internal structure. As shown in FIGS. 6 and 7, the present embodiment has almost the same structure as the first embodiment, except that the upper magnetic plate 30 is only one. In order to branch the magnetic flux from the ring-shaped permanent magnet 10 and divert the magnetic flux to the projecting magnetic bodies 16 and 17 and the projecting magnetic bodies 18 and 19, a horizontal air gap is provided between one of the upper and lower magnetic plates. If there is. In this example, the lower magnetic plates 13 and 14 form a horizontal air gap. FIG. 8 shows the magnetization distribution of the ring-shaped permanent magnet 10, and FIG. 9 shows the state of the magnetic flux density vector distribution.
[0039]
In the present embodiment, since the magnetic path is formed on the upper part of the ring-shaped permanent magnet 10, the amount of magnetic flux diverted to the projecting magnetic bodies 16 and 17 and the projecting magnetic bodies 18 and 19 is reduced, but the upper Since only one magnetic plate 30 is required, the number of parts is reduced, and it is easy to manufacture. Further, when the rotational position sensor is fixed on the lower surface, the upper portion is on the outside, but there is also an effect that the influence on the sensor output due to the intrusion of the magnetic material from the outside can be reduced.
[0040]
A third embodiment of the present invention is shown in FIG. In this embodiment, holes 31 and 32 are provided in the magnetic plates 11 and 12 in the structure of the first embodiment. The magnetic resistance distribution in the magnetic path of the magnetic plates 11 and 12 can be adjusted by the shape and size of the holes. Thus, the linearity between the magnetic flux density detected by the Hall element and the rotation angle is improved as compared with the rotational position sensor of the first embodiment. Further, the linearity can be further improved by making similar holes in the magnetic plates 13 and 14. Although the case where one hole is provided in each magnetic plate is shown here, the present invention is not limited to this, and two or a plurality of holes may be used. The same applies to the following.
[0041]
A fourth embodiment of the present invention is shown in FIG. In this embodiment, holes 31 and 32 are provided in the magnetic plate 30 in the structure of the second embodiment. In this embodiment, the linearity between the magnetic flux density detected by the Hall element and the rotation angle is improved compared to the second embodiment.
[0042]
A fifth embodiment of the present invention is shown in FIG. In this embodiment, in the first embodiment of the present invention, the ring-shaped permanent magnet 10 magnetized into two poles in FIG. 2 is replaced with a one-pole halved permanent magnet 10a. The permanent magnet 10a is magnetized upward or downward in the rotation axis direction. In this case, the magnetic flux entering the magnetic plate 11 is approximately proportional to the vertical projection area of the permanent magnet 10a onto the magnetic plate 11, and this vertical projection area is proportional to the rotation angle of the permanent magnet 10a. For this reason, the magnetic flux density detected by the Hall element 21 is proportional to the rotation angle of the permanent magnet 10a. Thereby, by sensing the magnetic flux density detected by the Hall element 21, the rotation angle of the ring-shaped permanent magnet 10a, that is, the rotation angle of the shaft 15 can be detected.
[0043]
A sixth embodiment of the present invention is shown in FIG. In this embodiment, in the second embodiment of the present invention, the ring-shaped permanent magnet 10 magnetized to the two poles in FIG. 7 is replaced with a one-pole halved permanent magnet 10a. The magnetic flux generated from the permanent magnet 10a enters the magnetic plate 30 and is shunted toward the protruding magnetic bodies 17 and 19, passing through the Hall elements 21 and 22 and the protruding magnetic bodies 16 and 18, respectively. The magnetic plates 13 and 14 are entered to form a magnetic path that returns to the permanent magnet 10a. The diversion ratio of the magnetic flux to the protruding magnetic bodies 17 and 19 is substantially determined by the ratio of the area of the vertical projection surface of the permanent magnet 10a to the magnetic plate 13 and the ratio of the vertical projection surface of the permanent magnet 10a to the magnetic plate 14. For this reason, the magnetic flux density detected by the Hall element 21 is proportional to the rotation angle of the permanent magnet 10a. Thereby, by sensing the magnetic flux density detected by the Hall element 21, the rotation angle of the ring-shaped permanent magnet 10a, that is, the rotation angle of the shaft 15 can be detected.
[0044]
A seventh embodiment of the present invention is shown in FIG. In the present embodiment, a rotor is formed by the ring-shaped permanent magnet 10, the magnetic yoke 35, and the shaft 15 that supports the ring-shaped permanent magnet 10, and the magnetic plate 31 surrounding the ring-shaped permanent magnet 10 from the outside; A stator is formed by the Hall elements 21 and 22 inserted in the air gap of the magnetic plate 31. The ring-shaped permanent magnet 10 is magnetized in the radial direction, and is magnetized in two poles when viewed on the outer circumferential surface over the entire circumference. That is, in the range of 180 ° in the circumferential direction, the other regions are magnetized outward in the radial direction and the other regions are magnetized inward in the radial direction. The magnetic plate portion 31a that forms the magnetic pole closest to the rotor of the magnetic plate 31 serves to collect magnetic flux from the ring-shaped permanent magnet 10, and the magnetic field distribution in the magnetic plate portion 31a is directly related to the Hall element 21, Therefore, the shape of the surface 31b in which the magnetic plate portion 31a directly faces the ring-shaped permanent magnet 10 needs to be uniform in the rotation direction of the ring-shaped permanent magnet 10. Absent. The magnetic flux collected at the magnetic plate portion 31a passes through the magnetic plate portion 31c, then passes through the Hall element 21, passes through the other magnetic plate portion 31c and the magnetic plate portion 31a, and is a ring-shaped permanent magnet. Return to 10. In the present embodiment, the magnetic plate portion 31a and the magnetic plate portion 31c are on the same plane, but the present invention is not limited to this. In FIG. 14, the magnetic plate portion 31 c may be three-dimensionally configured so as to pass before or behind the ring-shaped permanent magnet 10.
[0045]
An eighth embodiment of the present invention is shown in FIG. In this embodiment, in place of the protruding magnetic bodies 16, 17, 18, 19 in the first embodiment of the present invention, protruding portions 50a, 51a are provided on the magnetic plates 50, 51 shown in FIG. As shown in FIG. 16, the ring-shaped permanent magnet 10 is sandwiched from above and below, using protrusions 50 a and 51 a bent substantially perpendicular to the surface of the magnetic plate 50. At this time, by sandwiching the Hall elements 21 and 22 between them, a magnetic path substantially equivalent to the first embodiment can be formed, and the function of a non-contact rotational position sensor can be provided. According to the present embodiment, the magnetic plates 50, 51 are punched out compared to the shape in which the protruding magnetic bodies 16, 17, 18, 19 are arranged on the magnetic plates 11, 12, 13, 14 in the first embodiment. Since only the bending process of the projection parts 50a and 51a is sufficient, there is an effect that productivity is increased.
[0046]
A ninth embodiment in which the first embodiment of the present invention is applied to an actual machine will be described. In FIG. 17, the storage cover 41 of the target device whose rotation angle is to be detected is provided with a rotation shaft through hole 42 for projecting the rotation shaft, and a protruding magnetic film is formed on the outer surface of the storage cover 41. The magnetic plates 13 and 14 to which the bodies 16 and 18 are attached and the Hall elements 21 and 22 are mounted. A ring-shaped permanent magnet 10 and a shaft 15 are integrated on the rotating shaft of the target device. Further, the magnetic plates 11 and 12 and the rotational position sensor storage cover 40 are attached to the outside thereof. As an integral method, for example, the rotational position sensor storage cover 40 is made of resin, and the integral molding process of the magnetic plate and the resin by insert molding is excellent in productivity.
[0047]
In the above embodiments, the magnetic plates 11, 12, 13, 14, and 30 are illustrated as rectangular plates. However, the present invention is not limited to this, and other shapes, for example, a disk type. Alternatively, any shape such as a semi-disc shape, a fan shape, or a trapezoid shape may be used.
[0048]
Various non-contact rotational position sensors using permanent magnets exist, including the present invention. However, when incorporated in a target device, there is a possibility that a magnetic material may be placed near the non-contact rotational position sensor. This affects the output signal of a magnetically sensitive element such as a Hall element. Therefore, as a tenth embodiment, as shown in FIG. 18, a shield cover 45 attached with a magnetic material is attached to the storage cover 40 of the non-contact rotational position sensor 1000, so that a Hall element or the like made of an external magnetic material can be used. There is an effect that the influence on the output signal of the magnetically sensitive element can be reduced.
[0049]
An example of a throttle valve assembly to which a non-contact type rotational position sensor according to the present invention is attached will be described with reference to FIGS.
[0050]
A rotating shaft (rotating shaft) 203 (corresponding to the shaft 15) is rotatably supported on the main body 201. A throttle valve 200 controls the opening area of the air flow path of the main body, and is fixed to the rotary shaft 203 by screws. A resin cover 202 is fixed to the main body 201 with screws (210a-210c).
[0051]
A through hole 204 is formed in the resin cover 202. The tip of the rotating shaft 203 extends out of the resin cover 202 through the hole 204.
[0052]
A rectangular recess is formed around the hole 204 of the resin cover 202, and magnetic plates 13 and 14 having a hole 51 in the center are attached to the outer wall surface of the resin cover forming the recess by adhesion. ing. The magnetic plates 13 and 14 are divided in the horizontal direction, and gaps similar to the air gaps (a1, a2, b1, b2) shown in FIG.
[0053]
With the resin cover 202 attached to the main body 201, the tip of the rotating shaft 203 extends beyond the magnetic plates 13 and 14.
[0054]
An annular or semi-annular magnet 10 is fixed to an attachment piece 110 made of a resin material provided with an attachment hole at the center, and the tip of the rotary shaft 203 is press-fitted into the center hole of the attachment piece 110 to fix them.
[0055]
With this configuration, the magnet 10 having an outer diameter larger than the diameter of the hole 51 at the center of the magnetic plates 13 and 14 can be attached to the outer end of the magnetic plates 13 and 14 at the tip of the rotating shaft 203.
[0056]
Reference numeral 40 denotes a resinous auxiliary cover that covers a portion corresponding to the recess of the resin cover 204.
[0057]
Inside the auxiliary cover 40, the magnetic plates 11, 12 are fixed with adhesives at positions facing the magnetic plates 13, 14. The protruding magnetic members 16, 18 formed on the magnetic plates 13, 14 and the protruding magnetic members 17, 19 formed on the magnetic plates 11, 12 are a pair of gaps with the auxiliary cover 40 attached to the resin cover 202. G2 is formed.
[0058]
Hall elements 21 and 22 as magnetically sensitive elements are attached to the gap G2.
[0059]
Thus, the non-contact sensor shown in FIGS. 1 to 5A and 5B can be formed at the end of the rotary shaft of the throttle valve.
[0060]
In the embodiment, a motor 207 is mounted on the main body 201, and the torque of the motor 207 is transmitted to the throttle shaft 203 via the intermediate gear 205 and the final gear 206 fixed to the rotary shaft 203. Yes.
[0061]
Reference numeral 208 denotes a fixed shaft that supports the intermediate gear 205. In this embodiment, the intermediate gear 205 is made of a resin material, and the final gear 206 is made of a sintered alloy. This can suppress the electromagnetic noise generated by the motor 207 from being absorbed by the magnetic final gear 206 and affecting the magnetic circuit of the sensor.
[0062]
This effect can also be obtained by forming the intermediate gear 205 and the fixed shaft 208 that supports the rotation of the intermediate gear 205 from a magnetic material.
[0063]
In addition, when the last stage gear 206 is comprised with the magnetic material, it needs to consider acting as a part of magnetic path of the leakage magnetic flux which passes along a rotating shaft.
[0064]
Even if the final gear is made of a resin material, a metal part is required at the center to obtain a fixing force to be fixed to the rotating shaft. Since it becomes the magnetic path of the leakage magnetic flux which leaks through 10 rotating shafts, it is necessary to consider the magnetic action.
[0065]
Considering these points, it is necessary to set the diameter of the central hole 51 of the magnetic bodies 13 and 14 or the gap between the last gear side magnetic material portion and the magnetic plates 13 and 14.
[0066]
In this embodiment, the air gap G2 between the magnet 10 and the magnetic plates 13 and 14 is an air gap between the magnetic plates 13 and 14 and the rotating shaft 203, and between the magnetic plate and the magnetic member on the final stage gear 206 side. The air gap is configured to be smaller than any of the air gaps, and the leakage magnetic flux passing through the rotating shaft 203 is set to be as small as possible.
[0067]
【The invention's effect】
According to the present invention, in the shape of the opposing surface of the magnetic path on the stator side and the rotor side, even if the length in the direction perpendicular to the rotation direction is not uniform, ensuring a high degree of design freedom, There is an effect that sufficient performance can be obtained. Further, since the magnetic flux can be effectively collected on the mounting portion of the magnetic sensitive element, a highly sensitive non-contact rotational position sensor with high sensitivity can be obtained. Furthermore, when the permanent magnet to be used is magnetized in the direction of the rotation axis, sufficient detection sensitivity can be obtained even if there is no magnetic material other than the permanent magnet on the rotor side. Therefore, the moment of inertia of the rotor can be reduced, and therefore, the load of the actuator for driving the rotation can be reduced, and the response of the rotor can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing the appearance of a first embodiment of the present invention.
FIG. 2 is a diagram showing an internal structure of a first embodiment of the present invention.
FIG. 3 is a diagram showing a magnetization distribution of a ring-shaped permanent magnet which is a component of the first embodiment of the present invention.
FIG. 4 is a diagram showing a magnetic flux density vector distribution in the first embodiment of the present invention.
FIG. 5A is a view for explaining the operating principle of the non-contact rotational position sensor in the first embodiment of the present invention. (B) is the conceptual diagram which crossed YY of (a).
FIG. 6 is a diagram showing an external appearance of a second embodiment of the present invention.
FIG. 7 is a diagram showing an internal structure of a second embodiment of the present invention.
FIG. 8 is a diagram showing a magnetization distribution of a ring-shaped permanent magnet which is a component of the second embodiment of the present invention.
FIG. 9 is a diagram showing a magnetic flux density vector distribution in the second embodiment of the present invention.
FIG. 10 is a diagram showing the appearance of a third embodiment of the present invention.
FIG. 11 is a diagram showing the appearance of a fourth embodiment of the present invention.
FIG. 12 is a diagram showing the internal structure of a fifth embodiment of the present invention.
FIG. 13 is a diagram showing the internal structure of a sixth embodiment of the present invention.
FIG. 14 is a diagram showing the internal structure of a seventh embodiment of the present invention.
FIG. 15 is a diagram showing a shape before processing of a magnetic plate used in an eighth embodiment of the present invention.
FIG. 16 is a diagram showing the internal structure of an eighth embodiment of the present invention.
FIG. 17 is a diagram showing the internal structure of a ninth embodiment of the present invention.
FIG. 18 is a diagram showing the internal structure of a tenth embodiment of the present invention.
FIG. 19 is a conceptual diagram of a cross section taken along line XX in FIG. 20 (dimensional shapes and positional relationships are not necessarily the same, but functionally include the same members).
FIG. 20 is an exploded perspective view showing an embodiment of a throttle valve assembly to which the non-contact rotational position sensor of the present invention is attached.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 10a ... Permanent magnet, 11, 12, 13, 14, 30, 31, 50, 51 ... Magnetic plate, 15 ... Shaft, 16, 17, 18, 19 ... Protruding magnetic body, 21, 22 ... Hall element, 31a, 31c: Magnetic plate portion, 31b: Surface where the magnetic plate portion 31a directly faces the ring-shaped permanent magnet 10, 35 ... Magnetic yoke, 40 ... Storage cover, 41 ... Storage cover of target device, 42 ... Rotating shaft penetration 45, shield cover, 50a, 51a, projection, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, non-contact rotational position sensor.

Claims (10)

Ring-shaped or disk-shaped permanent magnets whose cross-sections are semicircular arcs in the region of the rotation direction and magnetized in opposite polarities,
A shaft holding the permanent magnet ,
An upper magnetic plate and a lower magnetic plate that sandwich the permanent magnet from a direction along the axial direction of the shaft ;
At least one of the upper magnetic plate and the lower magnetic plate is opposed to a position where the directions of the magnetic fields of the permanent magnets are opposite to each other by an air gap formed across the rotation center of the shaft. Separated in a horizontal direction with respect to a direction along the axial direction of the shaft ;
Between each of the separated pair of magnetic plates and the remaining one of the upper magnetic plate and the lower magnetic plate ,
A pair of projecting magnetic parts having a magnetic gap in which the magnetically sensitive element is disposed;
A magnetically sensitive element disposed in the magnetic gap of the pair of protruding magnetic body portions;
The rotor composed of the permanent magnet and the shaft is rotatable relative to the upper magnetic plate and the lower magnetic plate ,
The permanent magnet is magnetized in a direction along the axis of the shaft;
As the permanent magnet rotates, the amount of magnetic flux passing through the magnetic sensing element varies,
The magnetic plate is non-contact rotational position sensor, characterized in that to form a straight line path between the permanent magnet and the protruding magnetic body irrespective of the rotational position of the permanent magnet. 2. The non-contact rotational position sensor according to claim 1 , wherein the protruding magnetic body is formed integrally with the magnetic plate. 3. 2. The non-contact rotational position sensor according to claim 1 , wherein the width of the air gap between the permanent magnet and the magnetic plate in the direction along the axial direction of the shaft is 0.5 mm or more, preferably about 1 mm. A non-contact rotational position sensor. 2. The non-contact rotational position sensor according to claim 1, wherein the magnetic material has a magnetic flux density of 0.5 T or less. 3. 2. The non-contact rotational position sensor according to claim 1, wherein the pair of magnetically sensitive elements are Hall elements or Hall ICs. 2. The non-contact rotational position sensor according to claim 1, wherein the member for fixing the magnetic plate is manufactured by integral processing by resin molding. 2. The non-contact rotational position sensor according to claim 1, wherein at least one hole is provided near a projecting magnetic body of the magnetic plate or a portion for narrowing a magnetic flux. . The one of claim 1,
The assembly of the magnetic plates arranged in the direction along the axial direction of the shaft across the permanent magnet faces in a direction along the axis of the shaft with a larger interval than the thickness of the permanent magnet, A non-contact rotational position sensor provided with a uniform air gap on a surface facing the permanent magnet disposed on the surface. In claim 1,
Each of the magnetic plates is a non-contact rotational position sensor having a quadrangular shape. Claim 9
The pair of protruding magnetic bodies are non-contact rotational position sensors formed at target positions with the rotational shaft interposed therebetween.

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